Sustainable materials for electrochemical capacitors

Highly tunable properties of materials used for the construction of electrochemical capacitors make them a perfect choice for a broad scope of applications with high power demand. The ability to design the system according to the expected power/energy profile allows them being considered as powerful alternatives to conventional capacitors and batteries. Carbon materials with the developed specific surface area are the most common electrode components of electrochemical capacitors because of their cost, versatile form, availability, easiness of processing, and eco-friendly character. Biomass is frequently used for carbon production, however, among many natural organic materials, only some of them should be regarded as a useful precursor. Ongoing research brings many novel concepts of using bio-derived materials in high-performance electrochemical capacitors. This review article summarizes the progress on the applications of abundant biomaterials and materials derived from biomass in the field. Various 'green' resources have been used as precursors for activated carbons, as binders, or as gel (gelating) agents for solid-state electrolytes. The authors attempt to critically evaluate a commercial potential of these materials upon ongoing trends in research & development of electrochemical capacitors. Pros and cons of utilizing the selected biomass materials are provided and perspectives for their advanced processing are discussed.